Full Drainage Plan

Major development proposals (more than 5,000 square feet of new impervious surface area, or more than 5,000 cubic yards of gross cut or fill) generally require storm water detention and water quality treatment facilities designed by a professional engineer licensed in Washington.

Targeted Drainage Plan

Other developments (more than 200 but less than 5,000 square feet of new impervious surface area) generally have no detention or water quality treatment requirements. A Targeted Drainage Plan can either be for construction, or can be a conceptual plan usually associated with a land use action going to hearing. View the Targeted Drainage Plan Checklist (PDF).

Grading Plan

A grading permit is required for all grading that does not meet the exemption requirements of 30.63B. When no impervious surfaces are proposed but a grading permit is still required, use the Grading Plan Submittal Checklist (PDF).

Grading Application

Low Impact Development

Low Impact Development (LID) is now available for projects meeting LID Ordinance 30.63C (PDF), and is offered as an alternative. Use the 2005 DOE Manual if claiming credits in your detention pond sizing for using LID techniques.